In early 2017 we made a change to how we sold our Trailing Arm kits. That was to sell them in a more ala-a-carte fashion using standard off the shelf spacers, as well as having numerous options.
Overwhelming feedback was that a single complete kit that included a specifically designed upgrade for the C4 suspension components was preferred. So we’ve decided to return to it. A key part of our system is a spacer specifically designed for the C4.
The OE trailing arms are shaped much like a bone and are often referred to as “dogbones”. They have a circular cross-section with a larger feature on each end. This feature contains the OE rubber bushings and bushing sleeve. The figure below show the construction of an OE trailing arm.
Key components of our system: custom spacers (C4 specific)
On the frame side of the camber rods the spacers need to fit the width of the OE mounting bracket and sleeve the 16 mm through hole to accept a 12 mm bolt that is supplied in the kit.
On the knuckle side of the camber rods the spacers need to fit the width of the OE mounting point on the suspension knuckle. The spacers are designed to accept the OE 16 mm bolt. The rod end is already sized to do so.
Because our products us the OE mounting points we had to add spacers to take up the difference and ensure we could use the OE mounting hardware to ensure proper fastener strength.
On the frame side of the trailing arms the spacers need to fit the width of the OE mounting bracket and sleeve the 16 mm through hole to accept the OE 12 mm bolt. The figure below shows how this is accomplished.
The knuckle side is much simpler as it is a single shear type of attachment as opposed to the double shear attachment point of the frame side. The spacers are designed to accept the OE 16 mm bolt. The rod end is already sized to do so. The inner spacer acts to locate the center line of the trailing arm to the same place as the OE trailing arm. The outer spacer allows maximum rotation of the rod end while providing more strength than typical tubular spacers. The tapered spacer also provides safety as it will not allow the trailing arm to fully detach from the knuckle should the rod end ball come free from the rod end housing (an incredibly rare occurrence but theoretically possible nonetheless). The figure below shows these features.